/*
 *  FIPS-180-2 compliant SHA-256 implementation
 *
 *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
 *  SPDX-License-Identifier: Apache-2.0
 *
 *  Licensed under the Apache License, Version 2.0 (the "License"); you may
 *  not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *  This file is part of mbed TLS (https://tls.mbed.org)
 */
/*
 *  The SHA-256 Secure Hash Standard was published by NIST in 2002.
 *
 *  http://csrc.nist.gov/publications/fips/fips180-2/fips180-2.pdf
 */

#include "sha256.h"
#include <string.h>

/* Implementation that should never be optimized out by the compiler */
static void mbedtls_zeroize( void *v, size_t n )
{
	volatile unsigned char *p = v;
	while( n-- ) *p++ = 0;
}

/*
 * 32-bit integer manipulation macros (big endian)
 */
#ifndef GET_UINT32_BE
#define GET_UINT32_BE(n,b,i)                            \
do {                                                    \
    (n) = ( (uint32_t) (b)[(i)    ] << 24 )             \
        | ( (uint32_t) (b)[(i) + 1] << 16 )             \
        | ( (uint32_t) (b)[(i) + 2] <<  8 )             \
        | ( (uint32_t) (b)[(i) + 3]       );            \
} while( 0 )
#endif

#ifndef PUT_UINT32_BE
#define PUT_UINT32_BE(n,b,i)                            \
do {                                                    \
    (b)[(i)    ] = (unsigned char) ( (n) >> 24 );       \
    (b)[(i) + 1] = (unsigned char) ( (n) >> 16 );       \
    (b)[(i) + 2] = (unsigned char) ( (n) >>  8 );       \
    (b)[(i) + 3] = (unsigned char) ( (n)       );       \
} while( 0 )
#endif

void mbedtls_sha256_init( mbedtls_sha256_context *ctx )
{
	memset( ctx, 0, sizeof( mbedtls_sha256_context ) );
}

void mbedtls_sha256_free( mbedtls_sha256_context *ctx )
{
	if( ctx == NULL )
		return;

	mbedtls_zeroize( ctx, sizeof( mbedtls_sha256_context ) );
}

void mbedtls_sha256_clone( mbedtls_sha256_context *dst, const mbedtls_sha256_context *src )
{
	*dst = *src;
}

/*
 * SHA-256 context setup
 */
void mbedtls_sha256_starts( mbedtls_sha256_context *ctx, int is224 )
{
	ctx->total[0] = 0;
	ctx->total[1] = 0;

	if( is224 == 0 )
	{
		/* SHA-256 */
		ctx->state[0] = 0x6A09E667;
		ctx->state[1] = 0xBB67AE85;
		ctx->state[2] = 0x3C6EF372;
		ctx->state[3] = 0xA54FF53A;
		ctx->state[4] = 0x510E527F;
		ctx->state[5] = 0x9B05688C;
		ctx->state[6] = 0x1F83D9AB;
		ctx->state[7] = 0x5BE0CD19;
	}
	else
	{
		/* SHA-224 */
		ctx->state[0] = 0xC1059ED8;
		ctx->state[1] = 0x367CD507;
		ctx->state[2] = 0x3070DD17;
		ctx->state[3] = 0xF70E5939;
		ctx->state[4] = 0xFFC00B31;
		ctx->state[5] = 0x68581511;
		ctx->state[6] = 0x64F98FA7;
		ctx->state[7] = 0xBEFA4FA4;
	}

	ctx->is224 = is224;
}

#if !defined(MBEDTLS_SHA256_PROCESS_ALT)
static const uint32_t K[] =
{
	0x428A2F98, 0x71374491, 0xB5C0FBCF, 0xE9B5DBA5,
	0x3956C25B, 0x59F111F1, 0x923F82A4, 0xAB1C5ED5,
	0xD807AA98, 0x12835B01, 0x243185BE, 0x550C7DC3,
	0x72BE5D74, 0x80DEB1FE, 0x9BDC06A7, 0xC19BF174,
	0xE49B69C1, 0xEFBE4786, 0x0FC19DC6, 0x240CA1CC,
	0x2DE92C6F, 0x4A7484AA, 0x5CB0A9DC, 0x76F988DA,
	0x983E5152, 0xA831C66D, 0xB00327C8, 0xBF597FC7,
	0xC6E00BF3, 0xD5A79147, 0x06CA6351, 0x14292967,
	0x27B70A85, 0x2E1B2138, 0x4D2C6DFC, 0x53380D13,
	0x650A7354, 0x766A0ABB, 0x81C2C92E, 0x92722C85,
	0xA2BFE8A1, 0xA81A664B, 0xC24B8B70, 0xC76C51A3,
	0xD192E819, 0xD6990624, 0xF40E3585, 0x106AA070,
	0x19A4C116, 0x1E376C08, 0x2748774C, 0x34B0BCB5,
	0x391C0CB3, 0x4ED8AA4A, 0x5B9CCA4F, 0x682E6FF3,
	0x748F82EE, 0x78A5636F, 0x84C87814, 0x8CC70208,
	0x90BEFFFA, 0xA4506CEB, 0xBEF9A3F7, 0xC67178F2,
};

#define  SHR(x,n) ((x & 0xFFFFFFFF) >> n)
#define ROTR(x,n) (SHR(x,n) | (x << (32 - n)))

#define S0(x) (ROTR(x, 7) ^ ROTR(x,18) ^  SHR(x, 3))
#define S1(x) (ROTR(x,17) ^ ROTR(x,19) ^  SHR(x,10))

#define S2(x) (ROTR(x, 2) ^ ROTR(x,13) ^ ROTR(x,22))
#define S3(x) (ROTR(x, 6) ^ ROTR(x,11) ^ ROTR(x,25))

#define F0(x,y,z) ((x & y) | (z & (x | y)))
#define F1(x,y,z) (z ^ (x & (y ^ z)))

#define R(t)                                    \
(                                               \
    W[t] = S1(W[t -  2]) + W[t -  7] +          \
           S0(W[t - 15]) + W[t - 16]            \
)

#define P(a,b,c,d,e,f,g,h,x,K)                  \
{                                               \
    temp1 = h + S3(e) + F1(e,f,g) + K + x;      \
    temp2 = S2(a) + F0(a,b,c);                  \
    d += temp1; h = temp1 + temp2;              \
}

void mbedtls_sha256_process( mbedtls_sha256_context *ctx, const unsigned char data[64] )
{
	uint32_t temp1, temp2, W[64];
	uint32_t A[8];
	unsigned int i;

	for( i = 0; i < 8; i++ )
		A[i] = ctx->state[i];

#if defined(MBEDTLS_SHA256_SMALLER)
	for( i = 0; i < 64; i++ )
	{
		if( i < 16 )
			GET_UINT32_BE( W[i], data, 4 * i );
		else
			R( i );

		P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i], K[i] );

		temp1 = A[7];
		A[7] = A[6];
		A[6] = A[5];
		A[5] = A[4];
		A[4] = A[3];
		A[3] = A[2];
		A[2] = A[1];
		A[1] = A[0];
		A[0] = temp1;
	}
#else /* MBEDTLS_SHA256_SMALLER */
	for( i = 0; i < 16; i++ )
		GET_UINT32_BE( W[i], data, 4 * i );

	for( i = 0; i < 16; i += 8 )
	{
		P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], W[i+0], K[i+0] );
		P( A[7], A[0], A[1], A[2], A[3], A[4], A[5], A[6], W[i+1], K[i+1] );
		P( A[6], A[7], A[0], A[1], A[2], A[3], A[4], A[5], W[i+2], K[i+2] );
		P( A[5], A[6], A[7], A[0], A[1], A[2], A[3], A[4], W[i+3], K[i+3] );
		P( A[4], A[5], A[6], A[7], A[0], A[1], A[2], A[3], W[i+4], K[i+4] );
		P( A[3], A[4], A[5], A[6], A[7], A[0], A[1], A[2], W[i+5], K[i+5] );
		P( A[2], A[3], A[4], A[5], A[6], A[7], A[0], A[1], W[i+6], K[i+6] );
		P( A[1], A[2], A[3], A[4], A[5], A[6], A[7], A[0], W[i+7], K[i+7] );
	}

	for( i = 16; i < 64; i += 8 )
	{
		P( A[0], A[1], A[2], A[3], A[4], A[5], A[6], A[7], R(i+0), K[i+0] );
		P( A[7], A[0], A[1], A[2], A[3], A[4], A[5], A[6], R(i+1), K[i+1] );
		P( A[6], A[7], A[0], A[1], A[2], A[3], A[4], A[5], R(i+2), K[i+2] );
		P( A[5], A[6], A[7], A[0], A[1], A[2], A[3], A[4], R(i+3), K[i+3] );
		P( A[4], A[5], A[6], A[7], A[0], A[1], A[2], A[3], R(i+4), K[i+4] );
		P( A[3], A[4], A[5], A[6], A[7], A[0], A[1], A[2], R(i+5), K[i+5] );
		P( A[2], A[3], A[4], A[5], A[6], A[7], A[0], A[1], R(i+6), K[i+6] );
		P( A[1], A[2], A[3], A[4], A[5], A[6], A[7], A[0], R(i+7), K[i+7] );
	}
#endif /* MBEDTLS_SHA256_SMALLER */

	for( i = 0; i < 8; i++ )
		ctx->state[i] += A[i];
}
#endif /* !MBEDTLS_SHA256_PROCESS_ALT */

/*
 * SHA-256 process buffer
 */
void mbedtls_sha256_update( mbedtls_sha256_context *ctx, const unsigned char *input, size_t ilen )
{
	size_t fill;
	uint32_t left;

	if( ilen == 0 )
		return;

	left = ctx->total[0] & 0x3F;
	fill = 64 - left;

	ctx->total[0] += (uint32_t) ilen;
	ctx->total[0] &= 0xFFFFFFFF;

	if( ctx->total[0] < (uint32_t) ilen )
		ctx->total[1]++;

	if( left && ilen >= fill )
	{
		memcpy( (void *) (ctx->buffer + left), input, fill );
		mbedtls_sha256_process( ctx, ctx->buffer );
		input += fill;
		ilen  -= fill;
		left = 0;
	}

	while( ilen >= 64 )
	{
		mbedtls_sha256_process( ctx, input );
		input += 64;
		ilen  -= 64;
	}

	if( ilen > 0 )
		memcpy( (void *) (ctx->buffer + left), input, ilen );
}

static const unsigned char sha256_padding[64] =
{
	0x80, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};

/*
 * SHA-256 final digest
 */
void mbedtls_sha256_finish( mbedtls_sha256_context *ctx, unsigned char output[32] )
{
	uint32_t last, padn;
	uint32_t high, low;
	unsigned char msglen[8];

	high = ( ctx->total[0] >> 29 )
		   | ( ctx->total[1] <<  3 );
	low  = ( ctx->total[0] <<  3 );

	PUT_UINT32_BE( high, msglen, 0 );
	PUT_UINT32_BE( low,  msglen, 4 );

	last = ctx->total[0] & 0x3F;
	padn = ( last < 56 ) ? ( 56 - last ) : ( 120 - last );

	mbedtls_sha256_update( ctx, sha256_padding, padn );
	mbedtls_sha256_update( ctx, msglen, 8 );

	PUT_UINT32_BE( ctx->state[0], output,  0 );
	PUT_UINT32_BE( ctx->state[1], output,  4 );
	PUT_UINT32_BE( ctx->state[2], output,  8 );
	PUT_UINT32_BE( ctx->state[3], output, 12 );
	PUT_UINT32_BE( ctx->state[4], output, 16 );
	PUT_UINT32_BE( ctx->state[5], output, 20 );
	PUT_UINT32_BE( ctx->state[6], output, 24 );

	if( ctx->is224 == 0 )
		PUT_UINT32_BE( ctx->state[7], output, 28 );
}

/*
 * output = SHA-256( input buffer )
 */
void mbedtls_sha256( const unsigned char *input, size_t ilen, unsigned char output[32], int is224 )
{
	mbedtls_sha256_context ctx;

	mbedtls_sha256_init( &ctx );
	mbedtls_sha256_starts( &ctx, is224 );
	mbedtls_sha256_update( &ctx, input, ilen );
	mbedtls_sha256_finish( &ctx, output );
	mbedtls_sha256_free( &ctx );
}
